The hydrotreating process of heavy hydrocarbon oils such as residual oils containing metal contaminants is a process in which a hydrocarbon oil is subjected to hydrodesulfurization and hydrodemetallation under high-temperature and high-pressure reaction conditions in a stream of hydrogen. The reactions are performed in a fixed bed reaction column charged with a demetallation catalyst having high demetallation selectivity, and a desulfurization catalyst having high desulfurization selectivity.
As the trend for using heavier feedstock oils, and the demand for reducing the load on the fluid catalytic cracking process performed after the hydrotreatment process continue to rise, the catalysts for hydrotreating process are required to satisfy high desulfurization performance and high catalyst stability. In order to reduce cracking and powderization during regeneration of a used catalyst, the catalysts should also desirably have sufficient strength and abrasion strength even before use.
PTL 1 describes a technique whereby a calcium compound is contained in a support primarily made of alumina to improve demetallation performance, and to reduce cracking and powderization even in regenerating a catalyst. Calcium has strong affinity to vanadium, and facilitates demetallation reaction. Calcium also allows vanadium to be immobilized in a catalyst, and improves regeneration performance. However, when a calcium compound having a small surface area is added, the surface area of the catalyst becomes smaller, and improvements are needed for desulfurization performance and desulfurization stability.
PTL 2 discloses a technique for making a wider pore distribution for a hydrotreating catalyst using an alumina-phosphorus support. The technique is intended to improve demetallation performance and deasphaltene performance. The technique is desirable in terms of demetallation reactivity of macromolecules such as asphaltenes, but needs improvements in desulfurization performance and desulfurization stability.